CH683674A5 - Automatic handling, sorting and sepn. of waste material - Google Patents

Abstract

A system for automatically sorting waste material has a preliminary stage in which items are sorted by size, density and low volume followed by sorting to specified criteria.Commencing with the random waste delivery (1) the various pre-sorting devices after conveyor separation (2) may include a beltsieve (4), ballistic separator (34), drumsieve (24), cyclone (26,27) sorteo, vibrator sieve (30), airblast or suction separator (40 to 45).Sorting by criteria in stage (9) is based on chemical composition and a spectrographic analysis is carried out on each item passing along the conveyor (10) by a polarising interferometer (11) and CPU (16) for selective sorting by the actuator (17).

Description

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The invention relates to a method for automatic sorting of waste material, in particular plastic waste, preferably in large quantities, and a device for carrying out the method, preferably with mechanical and motor-driven devices for sorting materials, bodies or the like. according to size and / or density and / or volume, such as vibrating sieves, sieve belts, sieve drums, vibrating devices, rotary wheel locks, air classifiers, ballistic sorters, suction devices and the like. individually or at least partially in combination, the preselected and optionally separated waste material being fed to a conveyor belt.

Waste, particularly urban and industrial waste, is naturally very heterogeneous both in terms of its size and its composition, which makes sorting relatively difficult. This difficulty increases particularly when it comes to processing part of the waste so that it can be reused. Now EP-B 82 815 describes a method in which it is surprisingly possible to sort the chemical constituents of the waste practically simply by sorting them by size, once it has been determined on the basis of a waste analysis which fractions have certain chemical properties. However, this document is not about reusing the material in the narrower sense, i.e. reuse in the area of application from which the waste originates, but rather incineration or composting.

Naturally, however, the requirements with regard to material quality are greater if the waste material is to be sorted in such a way that it can be reused. This applies in particular to the reuse of plastics, which, depending on their chemical composition, require different treatment. If too great inaccuracies arise during sorting, the entire reprocessing is questioned.

In the past, one mainly relied on manual sorting when it came to reprocessing plastic waste. Of course, a wide variety of methods are also known to determine the chemical composition - including of plastics of various materials. However, these methods of investigation fail in practice due to the large quantity of waste generated and have therefore hardly been used for these purposes.

The object of the invention is to create a sorting method for waste material, in particular plastic waste, with which even large amounts of waste can be sorted automatically with a high degree of accuracy. According to the invention, it is therefore proposed in a method of the type mentioned at the outset that the sorting is carried out in at least two steps, a pre-sorting being carried out in a first step, preferably according to a criterion deviating from the material composition of the waste material, and then a sorting in a second step is carried out according to material criteria.

This is where the invention makes use of the experience known from EP-B 82 815 that sorting according to criteria that differ from the material composition can already result in a certain concentration of individual chemical substances in the individual fractions. It is then much easier to carry out a selection based on the criteria of the material composition from these enriched fractions. Tests have also confirmed this.

In a further embodiment of the method according to the invention, it is proposed that the presorting is also carried out in at least two steps, this presorting preferably being carried out according to the size and / or density and / or volume of the waste material. These measures have proven to be advantageous and it is advantageous if the pre-sorting comprises at least one screening process. However, it is also advantageous to include at least one sieving process. However, it is also advantageous if this process step involves a visual process using gas, in particular air.

In order to increase the accuracy, it is provided according to a further characteristic of the invention that the waste material is preferably separated during the pre-sorting, but always before the sorting according to material criteria. In this way, easily separable volumes can be reliably checked in an advantageous manner.

Since the sorting of materials has to proceed relatively quickly after the pre-sorting, it is proposed in a further embodiment of the invention that a spectrogram of the waste material is determined in a second step in order to check or ascertain the material criteria of the already pre-sorted waste material, the spectral program preferably being interferometric , in particular by a Fourier analysis or a Fast Fourier analysis. Particularly precise results are obtained, for example, with a polarization interferometer, as described in WO 90/10191.

According to a further embodiment of the method according to the invention, it is proposed that, in particular when the spectrogram is determined interferometrically under illumination of the waste material, which preferably has different sizes and / or volumes, a distance measurement is carried out from a measuring head of the analysis device to the preferably isolated waste material during the analysis process and a signal derived from this distance measurement or the like as a correction signal. is set in functional connection with the preferably interferometrically determined spectrogram or this signal as a control signal for automatically setting a predetermined distance of the measuring head

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is used for the waste material to be tested.

The above-mentioned measures according to the invention advantageously simplify adaptation to large volume flows. The risk of contamination of the analyzer is also better avoided. If the materials to be tested have different materials, the use of reflected rays results in changes in the signal depending on the distance of the waste from the interferometer. Including the distance measurement in the method advantageously eliminates these adverse effects.

The sorting process can be carried out quickly if, according to a further embodiment of the invention, it is provided that spectrograms are stored as characteristic, preferably multidimensional target spectrograms for a variety of different material waste materials, taking into account different measuring distances, each with actual spectrograms in the sorting process tested waste material are compared and the result signal derived from the comparison is used at least as a control signal for the selective sorting process. The above-mentioned spectrograms result in multi-dimensional diagrams with various variables, including “wavelength”, “distance” and “material” and corresponding so-called clusters of characterizing points. The measuring distance can thus also be read from the spectrogram if desired, in which case a separate distance measuring device can be dispensed with.

In a device of the type mentioned at the outset for carrying out the method described above, it is proposed in a further embodiment of the invention that the conveyor belt is guided to a substance analysis device which has an interferometer, in particular a polarization interferometer, which is equipped with a reflected light illumination device for the Waste material is equipped, which preferably emits at least approximately parallel aligned light beams, the output signal of the interferometer being fed to an evaluation device for carrying out a Fourier analysis, in particular fast-Fourier analysis, which evaluation device is a comparison device for spectrograms derived from the analyzed waste material and has predetermined stored spectrograms, the output signal of the comparison device for controlling actuators, electrostatic and / or pneumatic and / or electromechanical ejectors, slides or the like. is intended for the tested and qualified waste material. This device enables the method according to the invention to be carried out efficiently and inexpensively, the measurement being carried out without contact.

The device according to the invention can be used particularly universally and the method can be carried out quickly if, in a further embodiment of the invention, it is provided that

Level measuring device for determining the distance of the waste material to be tested to the measuring head of the analysis device is provided, the output signal of which is fed to the evaluation device for preferably arithmetic compensation of the measuring distance and / or for automatically setting a predetermined measuring distance of the analysis device to the waste material on the conveyor belt.

It is advantageous if, according to the invention, the device for distance measurement is a non-contact active or passive distance measuring device for non-cooperative measurement objects, light, infrared radiation, microwave radiation or ultrasound being provided as the measurement radiation, and the measurement distance by signal transit time or measurement beam deflection according to trigonometric calculation rules can be determined.

Further details of the invention will become apparent from the following description of exemplary embodiments schematically illustrated in the single figure of the drawing.

The drawing shows several different options that can be used alternatively or cumulatively. So it is conceivable that, e.g. plastic material collected at collection points is transported by truck 1 in order to be fed to a separating device 2, if necessary after intermediate storage in an intermediate bunker. As can be seen, the individual plastic containers are each transferred separately to a conveyor belt 3, from where they are fed to a presort. As can be seen, this pre-sorting takes place in two steps.

In the first step, there is a sieving, for which purpose a sieve belt 4 is provided, which delivers the plastic material that has been passed through to a funnel, at the exit of which a cellular wheel sluice 6 is arranged for dispensing the material into a storage container 7.

As indicated by the dashed line 8, this material can, however, be fed directly to the downstream material sorting stage 9, which separates the material according to material criteria, i.e. performing a chemical analysis. In this case it is advantageous if the cellular wheel sluice 6 is operated step by step, so that the separation of the material is maintained on the transport paths 8. The material then arrives individually on a conveyor belt 10, which passes the individual parts past a polarization interferometer (later called device) 11, which is preferably designed in accordance with WO 90/10191. In contrast to this known embodiment, however, the device 11 works with an incident light lamp 12, so that the device 11 receives the light reflected by the material. The light source 12 is preferably associated with an optical system, in particular a mirror optical system 13, which aligns the illuminating beams 14 at least approximately in parallel, since this reduces the sensitivity of the device 11 to differences in distance.

Additionally or alternatively, a distance meter can be connected to the device 11. This distance meter is in the embodiment shown at 5

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Game formed by two photoelectric converters 15 located on a base, which receive the light originating from the light source 12 and reflected by the respective material. As such, one of the photoelectric converters 15 could also be replaced by a light source, but this is not necessary in the present case, since sufficient light is ensured by the light source 12. Otherwise, the distance measuring device 15 can be designed in any way, for example contain a diode row or as a transit-time range finder, e.g. with ultrasound. However, it is also possible to carry out the distance measurement by appropriate evaluation of the spectrogram.

In any case, an output line 20 produces an output signal of the device 11 which is determined by the interference and which is fed to an evaluation device 16 for performing a Fourier analysis, in particular a Fast Fourier analysis. The evaluation device 16 then preferably compares the spectrogram developed from this analysis with at least one stored target spectrogram in order to determine the chemical composition of the respective material, and actuates an actuator 17 accordingly. In principle, this works in a similar way to this is shown and described in EP-A 0 475 121. In particular, electrostatic and pneumatic actuators for throwing out the sorted-out parts are mentioned there, but the actuator 17 can also be a mechanical one, which, for example, has an electrical-fluid converter 18 for converting the signal obtained via an output line 19 into a corresponding fluidic, e.g. have a pneumatic signal on output lines 21, the output lines 21 controlling an actuating cylinder 22 for actuating a slide 23. As in EP-A 0 475 121, it is readily possible to arrange several such actuators 17 along the belt 10 in order to actuate one or the other, depending on the material to be sorted out.

However, the invention is by no means only applicable to plastic material that has already been pre-sorted, as is delivered by the trucks 1. Reference is made to DE-A 3 836 608, which mainly concerns the processing of so-called green waste, which often contains a certain proportion of plastics. According to this DE-A, a sieve drum 24, preferably consisting of several compartments with different hole sizes, is provided, to which a blower 26 for a wind sifter 25 receiving a fraction of the sieve diarrhea is connected. The classifying air is expediently operated in a circuit, for which purpose the air classifier 25 opens into a cyclone 27, within which the separated plastic fraction is deposited downwards, whereas the air again runs to the blower 26. On the underside of the cyclone 27, a cellular wheel sluice 106 is provided which, in a manner similar to the cellular wheel sluice 6, can expediently be operated step by step in order to deposit isolated plastic parts 29 on a passing conveyor belt 28.

The goods thus separated can in turn be fed from the conveyor belt 28 to the analysis and sorting stage 9 already described. It goes without saying that - particularly in the case of green compost - the screened fraction can carry a high proportion of fine compost parts with it, but this is separated out in the air classifier 25 in accordance with the disclosure of DE-A 3 836 698.

The various sorting methods can be used in combination with one another within the scope of the invention, for example if a vibration device 30 is used, which can be designed as a vibrating screen or as a known heavy part reader. If the material, e.g. Similar to the design of CH-PS 522 451, or DE-A 2 337 808, introduced via a filler neck 31 and reaches at least one sieve plate 104. However, several sieve plates can also be arranged one above the other with a decreasing hole cross section. Furthermore, a suction connection 32 is connected for the extraction of a fine fraction, and the vibration of the sieve bottom 104 can be designed such that the heavy parts collect on the top of this sieve.

In this way, in addition to the suction port 32, three outlets 32a, 32b, 32c can be provided for different fractions, which then each have a buffer (not shown here), e.g. Similar to the intermediate container 7, feed material, or deliver the material directly to the sorting line 9 via a multi-way switch 33.

Although it is preferred to connect a further screening after a screening, this can also be dispensed with if necessary. In the case of the sieve 4, a ballistic sorter 34 is connected downstream, which has a brush roller 35 according to WO 91/01817. As a result of the resilience of the surface of this brush roller 35, heavier parts will sink deeper and then be deflected downwards onto a belt conveyor 36, whereas lighter parts will be thrown off tangentially and fed to an intermediate store 38 via a conveyor 37. As can be seen, the parts from the conveyor 36 go directly to the analysis and sorting section 9, but the material coming from the conveyor 37 can also be fed to the analysis section 9 according to line 39.

Although it is therefore not preferred to carry out only one type of presorting, this can take place in several stages in which the material is fed to a filling funnel 40, which is expediently closed by a cellular wheel sluice 41. Below the cellular wheel sluice there is a conveyor channel 42 to which a number of wind classifiers, preferably zigzag wind classifiers 43, are connected.

In order to cause the material supplied to the channel 42 to climb up into the air classifier channels 43, impulse nozzles 44 can be provided at the entrance of a air classifier channel, which deflect the material into the air classifier channel.

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Alternatively or additionally, suction lines 45 are connected to the top of the air classifier channels 43. In any case, the lighter material is carried upwards, whereas the heavier material sinks back into the conveying channel 42 and is taken to the next air classifier. The arrangement can expediently be such that each of the channels 43 sorts out a different fraction, either by designing the flow conditions in these channels differently (higher or lower pressure or wind speed) and / or by making the channels different, e.g. are designed with different cross-sections.

The outputs of these air classifier channels 43 can in turn be fed directly to the analysis and sorting section 9 via a pipe switch 133 or to an intermediate bunker (not shown here).

It goes without saying that numerous variants are conceivable within the scope of the invention, in particular the various methods of presorting can be combined with one another, for example by using the sorting effect of fluidized beds for presorting. Sorting according to material criteria is also possible in a wide variety of ways, for example also chromatographically. If a spectrometer is used, the use of electromagnetic radiation in the near infrared range is cheap, but not a requirement; for example, light from the visible area can also be used. It is also understood that the incident light illumination is cheap, but it would also be conceivable to use a material, e.g. oblique to conduct shaft in which the probe of a spectrometer is housed.

Claims (10)

Claims 1. A method for the automatic sorting of waste material, characterized in that the sorting is carried out in at least two steps, a pre-sorting being carried out in a first step and then a sorting according to material criteria in a second step. 2. The method according to claim 1, characterized in that the presorting is carried out according to a criterion deviating from the material composition of the waste material, namely: preferably in at least two steps, or preferably this presorting according to size and / or density and / or volume of the waste material is made. 3. The method according to claim 1 or 2, characterized in that a separation of the waste material is preferably carried out during the pre-sorting, but always before the sorting according to material criteria. 4. The method according to any one of claims 1 to 3, characterized in that in order to check or determine the material criteria of the pre-sorted waste material, a spectrogram of the waste material is determined in the second step, the spectrogram preferably being interferometric, in particular by a Fourier analysis or a Fast Fourier analysis is determined. 5. The method according to claim 4, characterized in that, in particular in the case of interferometric determination of the spectrogram under reflected light of the waste material, which preferably has different sizes and / or volumes, a distance measurement of a measuring head of the analysis device for testing, preferably individualized, waste material is carried out during the analysis process and one signal derived from this distance measurement is set as a correction signal in a functional connection with the preferably interferometrically determined spectrogram or this signal is used as a control signal for automatically setting a predetermined distance of the measuring head from the waste material to be tested. 6. The method according to claim 5, characterized in that preferably for a variety of different material waste materials spectrograms are stored taking into account different measuring distances as characteristic, preferably multidimensional target spectrograms, these with actual spectrograms of each waste material tested in the sorting process are compared, and the result signal derived from the comparison is used at least as a control signal for the selective sorting process. 7. Device for performing the method according to one of claims 1 to 6, with devices for sorting materials and / or bodies according to size and / or density and / or volume, wherein the preselected waste material is fed to a conveyor belt, characterized in that Conveyor belt (10) is guided to an analysis device (11) which has a spectrometer. 8. Device according to claim 7, characterized in that a distance measuring device (15) is provided for determining the distance of the waste material to be tested from the measuring head of the analysis device (11), the output signal of the evaluation device (16) for preferably computational compensation of the measuring distance and / or for automatically setting a predetermined measuring distance of the analysis device (11) to the waste material on the conveyor belt (10), and that the device for distance measurement is preferably a non-contact active or passive distance measuring device for non-cooperative measurement objects, the measurement radiation being light, infrared radiation, Microwave radiation or ultrasound is provided, and the measuring distance can be determined by signal propagation time or measuring beam deflection according to trigonometric calculation rules. 9. Device according to one of claims 7 or 8, characterized in that at least one of the following features is provided: a) the spectrometer is associated with a reflected light illumination device (12, 13) for the waste material, which preferably emits at least approximately parallel aligned light beams; 5 10. Device according to one of claims 7 to 9, characterized in that at least one of the following features is provided: a) the sorting device for the presorting has at least one sieve (4, 24, 104); b) the sorting device for the presorting has at least one wind sifter device (27, 32, 43); c) it is a separation device (3), possibly in combination with a pre-sorting device, e.g. with a cellular wheel sluice (6, 106). 5 10th 15 20th 25th 30th 35 40 45 50 55 60 65 6 10th 15 20th 25th 30th 35 40 45 50 55 60 65 5 9 CH 683 674 A5 b) the spectrometer is designed as an interferometer, in particular a polarization interferometer, the output signal of which is fed to an evaluation device (16) for carrying out a Fourier analysis, in particular a Fast Fourier analysis; c) there is an evaluation device (16) with a comparison device for spectrograms derived from the analyzed waste material and predetermined stored spectrograms; d) the output signal of the spectrometer is fed to a controller of at least one actuator, such as electrostatic and / or pneumatic and / or electromechanical ejectors, slides (17 to 23).